unitialized variable in MT

For ages now, I’ve been getting the error message “MT::App::CMS=HASH(0x83a8228) Use of uninitialized value in concatenation (.) or string at lib/MT/App/CMS.pm line 2420.” when I post a blog entry. It doesn’t always happen but only sometimes. The last couple of posts are examples of where it happens. This morning I did a bit more digging and apparently it occurs when there is a problem with pings. I’ll do a bit more digging later but at least it doesn’t mean “error out of cheese, formatting hard disk”